Automatic furnace



Dec. 28, 1965 W. W. ROBSON, JR

AUTOMATIC FURNACE Original Filed Aug. 11. 1961 22 '8 FIG.

FIG.

5 Sheets-Sheet 1 Q 74 l I 172 I23 WILLIAM W. ROBSON, JR. BY

IN VEN TOR.

Dec. 28, 1965 w. w. ROBSON, JR 3,225,722

AUTOMAT I C FURNACE Original Filed Aug. 11, 1961 3 Sheets-Sheet 2 INVENTOR. WILLIAM W. ROBSON, JR. BY I ATT'Y Dec. 28, 1965 W. W. ROBSON, JR

Original Filed Aug. 11, 1961 AUTOMATIC FURNACE 3 Sheets-Sheet :5

IN V EN TOR:

WILLIAM W. ROBSON, JR.

United States Patent 3,225,722 AUTOMATIC FURNACE William W. Robson, Jr., 1621 Highland, Wilmette, Ill. Continuation of application Ser. No. 130,858, Aug. 11, 1961. This application Mar. 9, 1964, Ser. No. 351,275 13 Claims. (Cl. 110-38) This application is a continuation of application Serial No. 130,858 filed August 11, 1961, now abandoned.

This invention relates in general to furnaces and in particular to an automatic furnace system for hard fuels such as coal in which a grate structure is utilized whereby the heat energy is absorbed by the grate structure from hot coals and quickly conducted away therefrom and utilized to super heat secondary air to a high temperature. The rapid heat conduction saves the grate from harm and returns the heat to the fire box where it is used with air above the flame to form a highly com bustible mixture of dioxide gases to complete combustion without smoke or cooling the flame products to thereby increase the heating etficiency of the fuel and eliminate objectionable conventional smoke and fumes.

Heretofore, fuel burning devices, such as grates, shakers, pulverized coal burners, etc., have encountered common basic problems. Primarily, conventional devices endeavor to obtain maximum efficiency at minimum cost. But, in the attempt to obtain the theoretical 100% efiiciency, several factors are compromised involving the fuel, obnoxious fumes and smoke, and ashes, to name a few. The effective temperature of the byproducts of combustion, sometimes referred to as the air temperature in the fire box is the one factor most seriously abused. Furthermore, the conventional elements used as components in the furnace structure itself fall short of an efiectiveness hoped for with sacrifices made to be competitive upon the market.

Undoubtedly, one of the components causing diminution of hoped for results in conventional fuel burning devices has bene the grate on which the fuel burns. To increase the longevity of these grates, several expedients such as water cooling jackets, increased stock of material, or forced air have been used with the object of reducing the temperature of the grate in an endeavor emphasized to prevent failure. In the present invention, the object is to increase temperature and utilize it without harm to the elements and with improved results. Even in recent years with the development of new metals, although the failure time of grates has increased, the aim is still to reduce heat and the initial expense has increased as thesenew metals have been utilized still without benefits in heat conversion efliciency and longevity accomplished by the present invention.

It is therefore, the primary object of this invention to provide a hard fuel burning system which substantially overcomes the shortcomings of similar prior art devices and more substantially accomplishes the 100% efficiency mark desired in the burning of hard fuel in the fire box, Whether the furnace is idling or operating upon full demand.

It is a specific object of this invention to provide an improved grate structure in conjunction with a forced air system to absorb high heat from hot coals and trans mit it instantaneously to an area where it is utilized to heat air and return it to the fire box.

Another object of this invention is to provide an improved fuel burning system wherein high heat energy absorbed by an improved grate is transmitted to heat a tertiary forced air current directed into the flame of the burning fuel to complete combustion of the by-products of partial combustion escaping from the burning fuel.

A still further object of this invention is to provide an improved fuel burning system which substantially dries and aerates the hard fuel prior to it being deposited on the grate for burning.

Another object of this invention is to provide an im proved fuel burning system that automatically converts fuel to heat and disposes of the ash by conveying the fuel from a hopper to the combustion zone, partially burns it, oxidizes unburned by-products, and automatically removes the minute residue from the combustion zone.

A more specific object of this invention is to provide an improved perforate grate structure which permits pas sage therethrough of suflicient primary air to support primary combustion of the fuel resting thereon, but which is internally filled with a high heat conductivematerial, such as sodium, to provide a medium to absorb, transfer and deliver heat energy to heat secondary air for complete secondary combustion.

Other objects include a structural arrangement and mechanisms which may be located in a vault defined in part by its own coal hopper below ground and remain unattended for long periods of time, with the completely consumed by-products of combustion discharged at ground level to warm and maintain desired surface areas clear of ice or snow when the heat load is the greatest.

Another object is to provide a subsurface furnace vault in which the coal can be transmitted to a feed hopper and the ash returned to a hopper area for removal outside and away from the building being heated.

These, and other objects and advantages, will become more apparent from the specification following as illus trated in the accompanying drawings in which:

FIG. 1 is a fragmentary cross-sectional View in side elevation illustrating the relationship of the component parts of the fuel burning system of this invention with indicating arrows thereon illustrating the flow of air relative to the component parts;

FIG. 2 is a cross-sectional view in end elevation taken along the line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view in end elevation taken along the line 33 of FIG. 1;

FIG. 4 is a cross-sectional view in plane elevation taken along the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary cross-sectional view in front perspective of the grate used in the fuel burning system of this invention;

FIG. 6 is a fragmentary partially sectioned enlarged view illustrating the relationship of the actuating mechanism and fuel feed control for the grate; and

FIG. 7 is a sectional view in side elevation similar to the view in FIG. 1 illustrating an alternate relationship of the component sections.

By way of generalization for a better understanding of the detailed description to follow, the fuel burning system of this invention is primarily characterized by the relationship of the component parts made possible with the fulfilment of the object to conduct high heat from the fire bed coals rapidly by a grate section having a heat conducting medium, such as, sodium to instantaneously transfer heat energy absorbed by the grate from the fire box at one end to a stream of air at the other end. The

air passes over the heat dissipating end of the grate and carries away the heat energy carried by the sodium from the fire box. Two advantages are thus attained; first, the secondary air is pre-heated and will attain a temperature almost as high as the ignition temperature of the burning fuel within the combustion chamber, and secondly, the grate is maintained at a lower overall temperature which ultimately increases its life span. Thereafter, the preheated air is returned to the fire box above the flame and directed downwardly onto the burning fuel, thereby carbureting and driving the unburned gases back to the flame at a high temperature to insure complete combustion of all fuel components with no cooling off or chilling of the effective working temperature of the lay-products of combustion above the burning fuel.

The fuel burning system of this invention is further characterized by providing a compact unitary unit which is fully automatic and self-contained having a fuel storage area, a combustion area and a residue area, all of which are interconnected and disposed in a vault underground unattended for long periods of time. The only manual operation required in placing thef uel system of this invention in operation is the depositing of the fuel into the storage area, initial ignition and periodically removing the unburned residue, which is very little since the system provides pure ash from the combustion of the material or fuel.

The fuel burning system of this invention has been illustrated in the drawings as being positioned below the ground level and is primarily used with a hot water, steam or forced air heating system for buildings such as large apartments, oflice building or factories. It is to be understood that this is by way of illustration only to clearly highlight the distinguishing and novel features of isolating this system. The system is readily usable also for all normal installations similar to prior devices of like character.

Referring now to FIGS. 1, 2, 3 and 4, the fuel burning system of this invention is contained within a unitary housing 10, which is divided into substantially three equal sections, a storage section 12, a combustion section 14, and an operating or mechanism section 16. The housing is preferably formed from a noncorrosive sheet metal since the system, in its compact unitary form, has its greatest adaptability in use when positioned below the ground level. Several advantages are readily apparent from having the system below the ground when placed adjacent to a factory or apartment buildings. 'First, the greater portion of the system will be below the frost line permitting the ground to serve as a natural insulation.

.heated, large quantities of undesirable moisture in the fuel and fuel storage section will be kept to a minimum which in turn aids in attaining efficient and complete combustion. Another side advantage is attained by having the system just below the ground level, in that a vehicle may be parked directly above the system during cold weather to maintain the vehicle in a warmed condition to permit ready starting.

The storage section 12, as well as the combustion section 14, will vary in size depending upon the heat capacity desired. Centrally mounted in the peak of the storage section 12 is an opening 18 through which the fuel is deposited into the storage area. A cover member 20, of conventional design is positioned flush with the road surface 22 and is readily removed and replaced. Retained below the cover member in the opening 18 is a magnetized conical member 24 which will collect any metallic objects which might inadvertently be in the fuel as it is being deposited in the storage section.

A fuel feed conveyor 26, which angularly extends across the storage section 12, through the combustion section 14 and into the mechanism section 16, has its receiving end 28 adjacent the bottom of the storage section. The complete operation of the conveyor 26 will be readily understood as the description continues.

Mounted adjacent a dividing wall 30, between the storage section 12 and the combustion section 14, is a residue system which is indicated generally by the nu meral 32. The residue system 32 includes a storage area 34, which may be readily removed for emptying, and a conveyor 36 which extends the full height of the fuel burning system with its lower pickup end 38 opening into a residue chamber 40 in the combustion section 14. The discharge end 42 empties into the removable storage are-a 34.

The residue conveyor 36 is powered by a motor 44 mounted adjacent the discharge end 42 and is controlled by a pressure sensitive switch mechanism 46 positioned just below the discharge opening on the end 42. When operating, if there is no residue being discharged to contact the switch 46, the motor 44 will be deenergized. The control of the conveyor 36 may also be readily controlled entirely by a timing mechanism interconnected with the motor 44.

The combustion section 14, often referred to as the fire box, is designed and constructed basically as the prior art devices of similar nature. An exhaust duct 48 is centrally formed in the upper peak of the combustion chamber and provides an upper perforated plate or grill 50 designed to set flush with the pavement 22. A plurality of water conduits 52, which are interconnected to a hot water recirculating heating system in a building "by way of example, are mounted adjacent the side walls, the upper wall and extending across the open space in the fire box below the exhaust duct 48. The water in the conduits 52 will absorb the heat energy created as the fuel burns. To assist in the absorption of this heat energy, a plurality of baffles 54, formed from fire brick, are angulary disposed across the combustion section to force circulation of the hot air back and forth, as it rises, into contact with the conduits 52 before passing through the exhaust duct 48 to the atmosphere.

A bottom wall 56 of the combustion section, having openings (not shown) therethrough for the passage of air, is augularly secured above the bottom or lower peak of the housing 10. The fuel feed conveyor 26, extending from the storage section 12, is secured to the under surface of the bottom wall 56 as best seen in FIG. 1.

A plurality of grate support members 58 are secured to the upper surface of bottom wall 56 on which a grate 60 may reciprocate as will be further described. The members 58 also provide divider walls to form a plurality of individual compartments 57 beneath the grate whereby the flow of primary air may be varied for different sections of the grate.

Adjacent the dividing wall 30, between the storage section 12 and combustion section 14, is a residue chamber -40 having an inwardly extending front wall 62 which terminates just below and behind the free end 64 of the grate 60. As the residue is forced from the end of the grate 60, it will be directed outwardly and downwardly into the chamber 40 to be picked up by the conveyor 36 and deposited in the residue storage area 34.

Referring now more specifically to FIG. 5, the grate 60 is formed from a plurality of elongated hollow members 66 which extend across the combustion section 14 and into the mechanism section 16. Each of the members 66 provide spaced recessed areas 68 on the sides thereof, whereby, when assembled in an abutting relationship, they form a grate having a plurality of air passages or ducts. As best seen in FIG. 1, the extended or free end 64 is augularly contoured in an upwardly direction relative to the slope of the grate. This angular offset at the end provides sufficient resistance to the burning fuel to keep it from dropping directly into the residue chamber 40. By permitting a small accumulation of the residue at the end of the grate, additional time is made available for further burning and to utilize any heat energy in the residue before dropping into the residue chamber 40.

Each of the hollow elongated members 66, preferably formed from stainless steel, has the entire volume thereof filled with sodium.

The high heat conductivity of the sealed sodium quickly distributes the high heat of the grate portion that is in contact with the burning coals over adjacent and remaining portions of the grate, to level the temperature of the grate yet as compared with grates that are cooled with Water the temperature of the grate remains above the ignition temperature of the coal. Thereby during Off periods of heat demand the grates embodying the invention will maintain combustion and start combustion of fresh coal that is gradually fed to it rather than permit combustion to die out which otherwise would occur with water cooled grates.

For instance with water of low heat conductivity of necessity circulated through the grate from the lower part of a boiler, the water circulates quite rapidly convectively and the temperature of the grate cooled by it can drop to less than the boiling point of the water over the grate which is not contacted by live coals and this chill gradually encroaches upon the live coal area and chills out the combustion with no reignition during Off periods of heat demand. Assuming the average ignition temperature of a reasonably good grade of coal to be 500 F. and the water temperature in the grate around 200 F. not only does the combustion go out but the coal is converted into coke at the diminishing temperature and reignition or kindling of coke is around 1400 F. Thus combustion is lost and the difficulty of restart for an On period of heat demand is greatly increased. This is eliminated with the grate embodying the invention because as long as there are live coals contacting the grate there will be enough temperature bordering same to ignite new coal when the air moving through the grate is only off period combustion air,

At the other extreme with the heat demand On, the temperatures at the live coal contact can run as much as 3000 F. and if permitted would cause fusing and clinkers which presents other difii-culties but with the temperature leveling effect of the high heat conductivity and the cooling of air as described, clinker temperatures are avoided.

Thus the grate embodying the invention serves not only a novel and useful purpose in a furnace combustion system for heat demand periods but as a unit itself serves in a novel and useful way to maintain combustion over long Off periods of furnace operation. The temperature of the grate remains leveled within a narrow range of from 1000 F. to 1500 F. in providing the performance described.

In this connection it is to be noted that during On periods of heat demand the sodium transmits the heat energy absorbed by the grate to the outer end of the grate disposed in the mechanism section and is utilized to preheat a source of secondary air as will be explained. Sodium is utilized as the conducting medium for the heat energy absorbed because of its instantaneous reaction, its high boiling point and its non-corrosive effect on the grate material.

,14. An outer wall 72 of the hopper does not extend to the peak of the housing which permits the passage of air to flow over and downwardly on the outer side of the wall in a channel formed by a parallel partitioning wall 74. The lower portions of the wall 72 and 69 are angled inwardly to funnel the fuel to a spreader 76 which is rotatably secured at the bottom of the hopper. The lower end of the partitioning wall 74 is integrally formed with a lower wall 78 which extends inwardly and downwardly to join the end wall 69 of the combustion section 12 well above the bottom or lower peak of the housing 10. Thus, it is seen that the hopper 70 is entirely disposed within an enclosed chamber.

Turning now to FIG. 6, the grate 60 extends through the side wall 69 and the partitioning wall 74 with an end 80 thereof secured to a portion 82 of heat insulating material which is in turn secured to an actuating mechanism indicated generally by the numeral 84.

The actuating mechanism 84 provides an elongated angular bracket 86 which is secured to the partitioning wall 74. An end portion 88, secured to the insulating portion 82, provides a depending lug 90 for interference contact with an abutment 92 integrally formed on the bracket 86. A plurality of tension springs 94, having one end secured to end portion 88 and the other end secured to the bracket 86, retains the grate in the rearward position wherein the lug 90 is in contact with the abutment 92. A cam member 96, journalled in the bracket 86, in juxtaposition for contact with the end portion 88, is rotated by a chain member 98 driven by a motor 100 mounted on the bracket 86. It is readily apparent that as the cam member 96 contacts the end portion 88, the grate 60 will be slowly forced inwardly a short distance and when the cam passes the end portion 88, the grate will be rapidly returned, by the force of the tension springs 94, until the lug 90 contacts the abutment 92.

A suitable ratchet, pawl and linkage arrangement (not shown) connects the grate 60 with the spreader 76. As seen in FIG. 6, the grate 60 is disposed just below the spreader 76 and the outlet of the hopper 70. As the grate 60 moves inwardly, through the action of the actuating mechanism 84 just described, the ratchet and pawl arrangement will rotate the spreader 76 sufficiently to deposit a supply of new fuel from the hopper 70 to the grate 60. As the grate returns to its normal position, by the action of spring 94, the jarring force created as the lug 90 contacts the abutment 92 will cause the burning fuel on the grate to shift slightly towards the extended end 64 of the grate with the residue at the extreme end thereof being forced off the end and into the residue chamber 40. It is to be understood that the jarring force required to move the coal on the grate and to dispense the ash from the extended end thereof may be created as the grate moves inwardly into the fire box rather than on the return motion with the same desired results.

By providing a compartment spreader 76 directly below the hopper 70, the danger of hopper fire is completely eliminated since the hopper is completely sealed from the burning coals on the grate.

The discharge end 102 of the fuel feed conveyor 26 terminates in the space below the lower wall 78 and the bottom of the housing 10. A drive motor 104 is mounted on the conveyor 26 and drives not only the conveyor but a feeder 106, which is connected in sealed relationship to the discharge opening of the conveyor.

Still referring primarily to FIGS. 1 and 3, a secondary air blower 108 and motor 109 is mounted on the bracket 86. Air is drawn to the inlet of the blower from the atmosphere through a grate 110 mounted in the upper portion of the mechanism section 16. An outlet line 112 from the blower 108 extends downwardly, provides a side opening for connection with the feeder 106 and the end thereof terminates in the hopper 70. As the feeder deposits the fuel into the discharge line 112, the flow of air conducts the fuel into the hopper 70 and discharges it with a spraying action. The fuel tumblesdownwardly into the funnel portion of the hopper and into the spreader 76 ready to be deposited on the grate 60 for burning as previously described. The flow of air passing in line 112, having carried the fuel to the hopper 70, is directed over the hopper wall 72 and downwardly through the channel formed by the wall 72 and the partitioning wall 74. The inwardly sloping lower portion of the hopper wall 72, which provided the funneling for the fuel towards the spreader 76, provides on the other side an expansive chamber for the downwardly flowing air to contact and pass through a greater area of the elongated grate 60. The air flow, as it passes through and around the grate, will absorb the heat energy stored in the sodium and grate material. A discharge conduit 114 is provided below the grate to conduct the now preheated air to an elevated header 116 which extends across the full Width of the grate 60 within the combustion section. Disposed at spaced intervals on the header 116 is a plurality of nozzles 118 which direct the preheated air towards the burning fuel.

The preheated air emitted from the nozzle 11% is at a temperature level substantially the same as the ignition temperature of the volatiles released from the coals to the air directly above the burning fuel since it has passed over such a large portion of the grate and is immediately directed towards the burning fuel. By providing substantially identical temperature of secondary air and escaping gases, the possibility of chilling or utilizing heat energy already generated by the fuel that releases the volatiles, to aid in forming a combustible mixture with the escaping gases for further combustion, has been eliminated.

Although the primary source of inlet air to the blower 103 is directly from the atmosphere through the grill 110, a secondary but smaller air inlet line 120 is connected to the fuel feed conveyor 26 just ahead of the conveyor discharge opening. By drawing a portion of the inlet air from the conveyor, much of the moisture in the fuel that is in the conveyor and in the storage section 12 will be withdrawn to provide a dryer fuel when deposited on the grate for burning.

A primary air blower 122 and motor 124 are mounted below the bracket 86 with air inlet port drawing air from the atmosphere through the grill 110 at the top of the mechanism section 16. The flow of air is discharged through the partition wall 69 below the fuel feed conveyor 26, into the compartments 57 formed by the dividers 58, and upwardly through the plurality of ducts 68 in the grate 60 for contact with the fuel thereon. The air flow from the blower 122 is diverted into separate ducts, each leading to one of the compartments 57, with dampers therein (not shown) to vary the flow of air to different sections of the grate 60.

Ladder rungs 126 are provided on the end wall of the housing to make the mechanism section 16 accessible for maintenance. A further supplementary provision is the installation of a conventional sump pump 128 to remove any collection of moisture at the bottom of the housing 10 since the grill 110 is directly open to atmosphere. Although not shown in the drawings, a protective housing may be readily adapted to cover the actuating mechanisms, motors and blowers to further protect them from the elements of weather.

Referring now to FIG. 7, an alternate arrangement of the three primary sections 12, 14 and 16 is illustrated. The component parts and the operation of these parts are identical as described for the preferred embodiment. In the alternate embodiment, the storage section 12 has been shifted to the opposite end of the system with the residue storage chamber 34 remaining in the same position as before.

Two primary advantages are gained by shifting the fuel storage section 12 to the other end of the system; first the length of the fuel feed conveyor 26 is materially reduced, and secondly, the partitioning wall 130 between the mechanism section 16 and fuel storage section 12 may be provided with a removable panel or door 132 to permit ready removal of the grate 60 when necessary for repairs.

It is of the utmost importance, in deriving maximum efiiciency from a fuel burning system of this character, to provide secondary preheated air at a temperature as close as possible to the temperature of the air above the burning fuel to attain secondary combustion of escaping gases Without chilling or reducing the work heat energy already generated by the fuel. It is for this reason that it is necessary to absorb as much heat in the grate as possible rather than to dissipate it in an attempt to extend the longevity of the grate as found in the prior art devices. It is readily understood from the above description that the more heat absorbed by the grate utilized in the fuel burning system of this invention, the higher the temperature of the secondary air will be since the secondary air is heated from one end of the grate which in turn will ultimately lower the overall grate temperature and increase its longevity.

Having described the various components of the system of this invention in detail and to some degree the operation and function of each component, the following description is directed towards the overall operation of the system.

With the initial ignition having been accomplished, the secondary air blower 108 is actuated and remains running at all times. The primary air blower 122, having been actuated to accomplish the initial ignition forces the heat generated upwardly into contact with the conduits 52 to heat the water circulating therein with the heating system in the building. Once the heating system has stored sufiicient heat, the necessity of new fuel and primary air is reduced. On demand for additional heat, the motor 104 will be energized to deposit fuel into the air line 112. At the same time, the motor will be energized to actuate the grate 60 which will permit the release of new fuel from the spreader 76. As the grate is removed and new fuel is added, the residue or ash on the end of the grate will drop into the residue chamber 40. Until the demand for additional heat has been satisfied, new fuel will continue to be deposited on the grate.

The residue system motor 44, preferably actuated by a timer to periodically collect the residue from the chamber 40, deposites the ash in the storage area 34. The timer and motor 44 are interconnected with the switch mechanism 46 and a delay circuit is provided whereby the motor 44, when actuated, will continue to run for a period long enough to bring the ash or residue from the chamber 40 to the storage area 34 at which time the switch mechanism 46 will be the controlling mechanism. As long as the conveyor 36 discharges residue, which contacts the switch mechanism 46, the circuit energizing the motor 44 will remain closed. Once all the residue has been deposited in the storage area 34, the switch mechanism 46, being spring loaded, will move towards the open position and break the circuit to the motor 44.

Thus, it is readily understood that the new fuel will be automatically deposited for burning on demand for more heat and the residue will be automatically removed to an area readily accessible for removal.

Since the secondary blower 108 is in continuous operation, the grate 60 will remain substantially at a desired lower temperature and a constant supply of preheated secondary air will be continuously directed downwardly towards the flame to permit secondary combustion of escaping combustible fumes.

From the foregoing description, it will be readily apparent to those skilled in the art that the fuel burning sys tem of this invention has provided many improvements to attain the ultimate in efiiciency, yet provide the desired longevity of the operating components.

Many modifications may be made in the invention as set forth without departing from the spirit of the invention or the scope of the claims and therefore the exact form shown is to be taken as illustrative only and not in a limiting sense.

What is claimed is:

1. An automatic furnace system for burning hard fuel comprising a housing including a combustion section, a fuel storage section, an ash storage area, and a mechanism section; a grate comprising a plurality of sealed compartments secured together in side abutting relationship and angularly disposed within the housing, said sealed compartments containing a high heat conducting material, one end extending into said combustion section and the other end extending into said mechanism section; means to transmit the fuel from the storage section to the grate within the combustion section, means to remove ash from the combustion section to the storage area, means to reciprocate said grate to cause downward movement of the fuel thereon, means to force air upwardly through the grate within the combustion section, means to force air downwardly through the grate within the mechanism section to preheat the air with grate heat, and means to conduct and direct the preheated air downwardly towards said grate within the combustion section to form a combustible mixture with escaping gases without reducing the temperature thereof.

2. The invention as set forth in claim 1 wherein said heat conducting material is sodium.

3. An automatic furnace system for burning hard fuel comprising a housing including a combustion section, a fuel storage section, an ash storage area and a mechanism section; a grate comprising a plurality of sealed compartments secured together in side abutting relationship and angularly disposed within the housing, said sealed compartments containing a high heat conducting material, one end extending into said combustion section and the other end extending into said mechanism section; a hopper; means to transmit the fuel from the storage section to the hopper; means to remove ash from the combustion section to the storage area, means to reciprocate said grate to cause downward movement of the fuel thereon, means to force air upwardly through the grate within the combustion section, means to force air downwardly through the grate within the mechanism section to preheat the air and means to direct the preheated air downwardly towards said grate within the combustion section forming a combustible mixture with escaping gases.

4. An automatic furnace system for burning hard fuel comprising a housing including a combustion section, a fuel storage section, an ash storage area and a mechanism section; a grate comprising a plurality of sealed compartments secured together in side abutting relationship and angularly disposed within the housing, said sealed compartments containing a high heat conducting material, one end extending into said combustion section and the other end extending into said mechanism section; a hopper; means to transmit the fuel from the storage section to the hopper; feed means on said hopper to supply fuel to the grate within the combustion section; means to remove ash from the combustion section to the storage area, means to reciprocate said grate to cause downward movement of the fuel thereon and actuation of said feed means; means to force air upwardly through the grate within the combustion section, means to force air downwardly through the grate within the mechanism section to preheat the air, and means to direct the preheated air downwardly towards said grate within the combustion section, forming a combustible mixture with escaping gases.

5. An automatic furnace system for burning hard fuel comprising a combustion section; a fuel storage section; an ash storage area; a mechanism section; an elongated grate comprising a plurality of sealed compartments containing a high heat conducting material secured together in side abutting relationship and angularly disposed with one end extending into said combustion section and the other end extending into said mechanism section; a hopper; a spreader member secured to said hopper adjacent the grate within the combustion section; a conveyor to transmit the fuel from the storage section to the mechanism section; means to remove ash from the combustion section to the storage area, means to reciprocate said grate to cause downward movement of the fuel thereon, means to force air upwardly through the grate within the combustion section, a blower to transmit the fuel from the mechanism section to the hopper and to force air downwardly through the grate within the mechanism section to preheat the air, and means to direct the preheated air downwardly towards said grate within the combustion section, forming a combustible mixture with escaping gases in the combustion section.

6. The invention as set forth in claim 5 wherein said heat conducting material is sodium.

7. An automatic furnace system for burning hard fuel comprising a housing including a combustion section, a fuel storage section, an ash storage section and a mechanism section; a grate comprising a plurality of sealed compartments secured together in side abutting relationship and angularly disposed within the housing, said sealed compartment containing a high heat conducting material, one end extending into said combustion section and the other end extending into said mechanism section; a hopper; first screw conveyor to transmit the fuel from the storage section to the mechanism section; second screw conveyor toremove ash from the combustion section to the storage area; a spreader rotatably secured in sealed relationship with said hopper; means interconnecting said spreader and said grate; means to reciprocate said grate to cause downward movement of the fuel and rotation of said spreader to supply new fuel thereon; means to force air upwardly through the grate within the combustion section; a blower to transmit the fuel from the mechanism section to the hopper and to force air downwardly through the grate within the mechanism section to preheat the air and means to direct the preheated air downwardly towards said grate within the combustion section, forming a combustible mixture with escaping gases in the combustion section.

8. An automatic furnace system for burning hard fuel comprising a housing including a combustion section, a fuel storage section, an ash storage area and a mechanism section; an elongated grate comprising a plurality of sealed compartments secured together in side abutting relationship and angularly disposed within the housing, said sealed compartments containing a high heat conducting material, one end extending into said combustion section and the other end extending into said mechanism section; a hopper; first screw conveyor having inlet end disposed in said storage section and discharge end in said mechanism section to transmit the fuel from the storage section; a second screw conveyor to remove ash from the combustion section to the storage area, a rotating spreader journaled below said hopper to dispense fuel on said grate within the combustion section; pivotal linkage members interconnecting the grate with the spreader; a rotating cam member to reciprocate said grate to cause downward movement of the fuel and rotation of the spreader to dispense fuel thereon; a first blower to force air upwardly through the grate within the combustion section, a second blower to transmit the fuel from the discharge end of said first screw conveyor to the hopper and to force air downwardly through the grate within the mechanism section to cool the grate and preheat the air and conduit means to direct the preheated air downwardly towards said grate within the combustion section, forming a combustible mixture with escaping gases.

9. The invention :as set forth in claim 8 wherein said heat conducting material is sodium.

10. An automatic furnace system comprising a combustion section, an ash storage area, a mechanism section, a grate including a plurality of side abutting elongated members formed from stainless steel having spaced recessed areas on abutting sides thereof defining a plurality of air passages therebetween and having a first portion disposed within said combustion section and a second portion disposed within said mechanism section, each of said elongated members having a sealed compartment extending its length filled with a high heat conducting material, means to dispose fuel on the first portion of said grate within the combustion section including an air blower means, means to remove ash from the combustion section to said storage area, means to flow air upwardly through the air passages in said first portion of the grate, said blower means moving air through the air passages in the second portion to absorb heat therefrom and downwardly on said first portion of the grate, and means within the mechanism section to vibrate the grate to cause movement of the fuel thereon.

11. An automatic furnace system comprising a combustion section, an ash storage area, a mechanism section, a grate comprising a plurality of sealed compartment filled with a high heat conducting material secured together in side abutting relationship and having a first portion disposed within said combustion section and a second portion disposed within said mechanism section, means to dispose fuel on the first portion of said grate within the combustion section including an air blower means, means to remove ash from the combustion section to said storage area, means to flow air upwardly through said first portion of the grate, said blower means conducting air through the second portion to absorb heat therefrom and then downwardly on said first portion of the grate, and means within the mechanism section to vibrate the grate to cause movement of the fuel thereon.

12. In combination with an automatic furnace system, a grate structure comprising a plurality of individual elongated hollow members each having a sealed compartment extending its length, said members being secured together in side abutting relationship, passage means formed be tween each abutting grates to provide airflow therebetween, each of said compartments being filled with an isolated body of a heat conducting medium having high heat conductivity.

13. In combination with an automatic furnace system, a grate structure comprising a plurality of individual elongated hollow members each having a sealed compartment extending a major portion of its length, said members being secured together in side abutting relationship and having recesses formed in spaced relationship in their abutting side walls along said compartments for passage of air therethrough, each of said compartments being filled with sodium.

References Cited by the Examiner UNITED STATES PATENTS 1,438,190 12/1922 Skelley 110-74 1,742,908 1/1930 Gibson 126-152 2,414,802 1/1947 Cushing 110-32 2,512,571 6/ 1950 Schweickart 11075 2,583,433 1/1952 Losch 126--152 X 2,629,350 2/1953 Gross 11032 3,005,446 10/1961 Kock 122-376 3,008,889 11/1961 Junkins 122-33 X FOREIGN PATENTS 105,724 2/ 1899 Germany.

FREDERICK L. MATTESON, JR., Primary Examiner.

JAMES W. WESTHAVER, Examiner. 

13. IN COMBINATION WITH AN AUTOMATIC FURNACE SYSTEM, A GRATE STRUCTURE COMPRISING A PLURALITY OF INDIVIDUAL ELONGATED HOLLOW MEMBERS EACH HAVING A SEALED COMPARTMENT EXTENDING A MAJOR PORTION OF ITS LENGTH, SAID MEMBERS BEING SECURED TOGETHER IN SIDE ABUTTING RELATIONSHIP AND HAVING RECESSES FORMED IN SPACED RELATIONSHIP IN THEIR 